Presentation
Patient with known ischemic heart disease and coronary stent insertion presents to ED post headstrike with nil loss of consciousness. No headache. GCS 15.
Patient Data
There are two large bilateral subdural hemorrhages of maximal thickness 19 mm on the right and 23 mm on the left. The subdural hemorrhages extend the length of the cerebral hemispheres. There is sedimentation layering reflecting acute on chronic subdural hemorrhage. There is no midline shift.
There are small to moderate size bilateral acute on chronic subdural hematomas. The largest on the left measures up to 11 mm. The one on the right measures up to 5 mm. These have decreased in size significantly since previous. No midline shift or mass effect is seen.
Case Discussion
The radiographic appearance of an acute on chronic subdural hemorrhage may vary depending on the type of re-bleed and the organization of chronic bleed.
It may appear isodense to the brain tissue, as a small acute bleed will mix with the lucent fluid of the chronic hemorrhage. Repeated trauma with active bleeding will cause a clot to form and would appear as a hyperdense lump within hypodense hemorrhage. It may also have a layered or ‘sedimentation appearance’. This is caused by the separation of extra-axial fluids of varying densities by internal membranes within the chronic clot.
As illustrated in the case study, the layered appearance of various blood components are separated by the internal membranes and gravity on the left. Contralaterally, a gradation from the chronic bleed anteriorly to the acute bleed posteriorly in the parietal parts of the skull is seen. This is due to the higher density of the acute bleed and supine position.
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